Human Development

A Cultural Approach

Chapter

2 Genetics and Prenatal Development

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Building Blocks of Life

• • • • Chromosomes DNA Genes Genomes

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Expression of Traits

• • Genotype-The totality of an individual’s genes Phenotype-Actual Characteristics  This is what is seen or observed and can include a wide range of things

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Studies of identical twins illustrate how different factors like smoking, sun exposure, depression and weight gain can influence aging. Age 52. The twin on the left smokes and has a history of more sun exposure, resulting in an older appearance than her twin of the same age. Photo: Dr. Bahman Guyuron

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Expression of Traits

• • • • Dominant Genes-Expressed characteristics Recessive Genes-Not expressed, although it is a part of the genotype (genetic background) Allele-Alternate form of a gene Dominant-Recessive Inheritance

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Table 2.1 Traits With Single-Gene Dominant–Recessive Inheritance

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Expression of Traits

• • Incomplete Dominance  Phenotype influenced primarily but not exclusively by the dominant gene Polygenic Inheritance  Interaction of multiple genes

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics The Sex Chromosomes

• • The 23 female rd chromosomes pair determine male or Males more vulnerable to X linked recessive disorders

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Genes and Environment

• Behavior Genetics  Estimating influence of genes and environment on development  Utilize twins to understand importance of genetics and tease out environment effects

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Genetic Basics Genes and Environment

• • Heritability  An estimate of the extent to which genes are responsible for differences among persons within a specific population Concordance Rates  Percentage that indicates degree of similarity in phenotype among pairs of family members

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Human Experience Conception and Prenatal Development

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Sperm and Egg Formation Cell Division

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Beginning of Life Conception

• • For conception to occur there must be a released ovum and a sperm.

Ovulation releases the ovum, and if sperm available, fertilization can occur.

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Germinal Period First 2 Weeks of Life

• During the travel from the fallopian tube to the uterus cell division is taking place    Blastocyst Trophoblast Embryonic disk

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Embryonic Period Week 3-Week 8

• Key Developments  Embryonic Layers Ectoderm Mesoderm Endoderm

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Embryonic Period Week 3-Week 8

• Key organs and structures are forming including      Heartbeat Eyes, nose and mouth Bone development Arm and leg buds Digestive system

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Fetal Period Week 9-Birth

• The longest period of prenatal development  Heartbeat can be heard  Movement can be felt   Responds to sounds Main impediment to viability is lung development

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

The Fetal Period Week 9-Birth

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Care Traditional Cultures and Beliefs

• • Prenatal beliefs are impacted by generational wisdom of the time These beliefs can include  Avoiding wine   Specific types of meat Certain types of hot, cold food   Witches Strong foods

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Care Science Driven Prenatal Care

• • • • Some current science-driven prenatal methods are derived from traditional cultures which includes massages Current care can vary by ethnicity and SES Developing world less likely to receive prenatal care Current focus on diet, exercise, and teratogens

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Map 2.1 Ethnic Variations in Prenatal Care within the United States How does prenatal care differ for White women compared with other ethnic groups? What economic factors might account for these variations?

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Care Diet

• • • Two key vitamins are iodine and iron Iodine deficiency tends to be a bigger issue in developing countries Iron is necessary for a healthy pregnancy

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Care Exercise

• • • Continued physical activity is encouraged during pregnancy Aerobic exercise encourages good cardiovascular health and positively benefits the fetus A Non-aerobic exercise called Kegel exercises are also encouraged

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Care Teratogens

• • • Teratogens are environmental and bodily conditions that could be harmful They can include tobacco, alcohol, prescription medications and other drugs The physical environment could also be a teratogen due to malnutrition or exposure to hazardous chemicals

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Safety sign. Source: http://www.compliancesigns.com

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Pregnancy Problems

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Chromosomal Disorders

• • Chromosomal disorders can occur because of an issue during meiosis  This may cause too many or too few chromosomes in the cells of the zygote Two types of chromosomal disorders are:  Sex chromosome disorders  Disorder on the 21 st Syndrome) chromosome (Down

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Sex Chromosome Disorders

• Sex chromosomal disorder can result from extra X, an extra Y, or only an X and no second chromosome  Common consequences of sex chromosome disorders include: Cognitive Deficit Abnormality in reproductive system at puberty

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Down Syndrome Trisomy 21

• • • • Identifiable by physical characteristics Cognitive Deficits  Speech problems  Mental retardation Social development varies Lower life expectancy

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Parental Age and Chromosomal Disorder

• • • Chromosomal disorders tend to NOT be passed from parent to child Relationship between maternal age and chromosomal disorders There may be a relationship between a father’s age and chromosomal disorders but it isn’t as clear

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Figure 2.7 Chromosomal Disorders and Maternal Age Why does the risk rise so steeply after age 40? Source: Reproductive Medicine Associates of New Jersey, 2002

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens

• Major teratogens exist in both developed and developing countries  Malnutrition  Infectious Disease   Alcohol Tobacco

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Timing of Teratogens

• • Teratogens can impact the developing fetus and embryo at any time There does appear to be a critical period of prenatal development centered in the embryonic period

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Timing of Teratogens

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Malnutrition

• • Rural nature of half the world’s population impacts nutrition Children’s health could vary based on country or area of conception

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Malnutrition

• • • Developed countries have food available but may have malnutrition May be deficient in specific vitamins or improper diet may lead to obesity  Maternal obesity is linked to baby complications Prenatal nutrition can also cause prenatal problems

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Infectious Diseases

• • Rubella (German Measles)  Exposure during embryonic stage can lead to heart abnormalities and mental retardation  Exposure during the fetal stage can lead to hearing problems and low birth weight Vaccination can help but Rubella remains widespread in less developed countries

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Infectious Diseases

• • AIDS (Acquired Immune Deficiency Syndrome) Three strategies can help prevent transmission  Effective medicines   Cesarean sections for AIDS-infected moms Infant formula in place of breast feeding

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Drugs-Alcohol

• • • Widespread damage in developed countries Fetal Alcohol Spectrum Disorder Increased effects as child develops

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Drugs-Tobacco

• • Maternal smoking increases risk of miscarriages, premature birth and low birth weight Infant effects include difficulty breathing and impaired heart functioning

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Drugs-Tobacco

• • Childhood effects include poorer language skills, attention and memory problems and behavior problems Second hand smoke by fathers is also detrimental

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Teratogens Drugs

• • • • Malnutrition and diseases are common in developing countries Alcohol and tobacco are common in developed countries Prescription drugs can be damaging Other teratogens include non prescription drugs, severe stress, pollution and radiation

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Prenatal Diagnosis

• • • Ultrasounds-Uses high frequency sound waves Amniocentesis-Utilizes amniotic fluid Chorionic Villus Sampling-Utilizes cells from forming umbilical cord

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Infertility Causes

• • For men three main causes  Too few sperm  Quality of sperm  Low motility For women many causes  One is ovulation

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Figure 2.9 Fertility and Maternal Age Why does fertility decline after the mid-twenties? Source: Reproductive Medicine Associates of New Jersey, 2002

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Infertility Treatments

• • Historical treatments of infertility included:  Giving more attention to wife to achieve mutual orgasm   Surgery on a woman’s anatomy Bloodletting Current treatments are more advanced

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Infertility Treatments

• Many treatments utilize Assisted Reproductive Technologies (ART)  Artificial Insemination   Injects sperm into woman’s uterus Fertility Drugs Mimic hormones involved in ovulation In-vitro fertilization Ova removed and fertilized outside the womb then placed into uterus

Human Development: A Cultural Approach

Jeffrey Jensen Arnett

Map 2.2 The “Infertility Belt” In certain countries in Central Africa, infertility rates are as high as 30%. The reasons for this are unclear although malnutrition and high rates of STIs are probable factors.

Human Development: A Cultural Approach

Jeffrey Jensen Arnett